The condition of a tennis racquet is an important concern for the serious tennis player. One of the important considerations is the tension of the strings which has an important influence on the effectiveness of the players skill. Numerous devices have been disclosed for measuring directly the tension of the racquet strings.
U.S. Pat. No. 3,834,225 to Burchett discloses a pivoting device having an end which clamps around the string and bends a string laid across the two sides of a channel. The tension is read as the force that is required to bend a section of string laid across the edges of a channel.
U.S. Pat. No. 4,055,999 to Cope is for a base and clamping structure intercoupled on opposite sides of the netting and a compressible spring loaded plunger mounted on the base for shifting movement against one face of the netting such as to deflect the netting to compress the plunger. A tension gauge is provided for measuring deflection of the netting.
U.S. Pat. No. 4,077,256 to Hollander disclose a hydraulic means for measuring the pressure required to move an abuttment member through a required distance.
U.S. Pat. No. 4,103,546 discloses a clamp supporting a spring housing telescoping an upper housing for biasing force against the strings with an indicator calibrated to measure the force against the strings vs. displacement.
U.S. Pat. No. 4,116,054 discloses a frame supporting a member movable against the strings and measuring device to measure displacement vs force.
U.S. Pat. No. 4,590,808 disclose a device for determining tension in grids having different size string areas and also for measuring the compressibility of tennis balls.
U.S. Pat. No. 4,747,314 to Huang discloses discloses a combination piston, pressure gauge, and weighing unit for measuring tension of racquet strings, flex of the shaft and weight of the racquet.
U.S. Pat. No. 4,794,805 discloses a spring loaded member that displaces the net vertical to the plane of the net with a dial indicator to measure distance of compression of a spring.
U.S. Pat. No. 4,846,002 to Brunner discloses a device having a member with a racket support surface joined to a cylinder containing a spring in compression by a bolt passing through the netting. Distance sensing electrical contacts in the recess of the member indicate when a reading is to be made.
U.S. Pat. No. 4,876,900 to Carney et al discloses a device adjustable to nettings of a racket having any one of a range of string sizes and spacings by using a set of interchangeable washers. Deflection of a known type of strain gauge is indicated by a crystal reeadout.
U.S. Pat. No. 5,048,352 to Ugarte discloses a tensioner with a pistol grip for applying a deflecting force and measuring string deflection.
U.S. Pat. No. 5,133,217 to Jordan discloses a tensiometer featuring a force applying probe forcing to the string between two supports and measuring the deflection by angular position of an indicator arm.
All of the above tensiometers have at least one disadvantage that is overcome by the present invention.